108 Mr. W. F. Barrett on a Physical 



1 also compared ozonized oxygen (not mixed with nitrogen as 

 in the air) with ordinary oxygen as to its power of producing 

 heat by combining with dcutoxide of nitrogen. I mixed, as in 

 the previous experiments, a measured volume of each with a 

 similar quantity of the deutoxide over water, but no difference 

 in amount of increase of temperature resulted. The ozonized 

 oxygen was obtained by transmitting a current from a DanielPs 

 battery (ten in series) through water acidulated with sulphuric 

 and chromic acids. 



It would only be occupying space unnecessarily, to give more 

 fully the details of the experiments, as the results were entirely 

 negative, no difference whatever in the amount of heat produced by 

 the combination in equal volumes of plain and ozonized oxygen was 

 found. If, therefore, any arrangement of particles exist in one 

 oxygen which does not in the other, these different states of 

 aggregation do not at all events require any force to trans- 

 mute them. 



Parsonstown, July 1864. 



XII. On a Physical Analysis of the Human Breath. By W. F. 

 Barrett, Assistant in the Physical Laboratory of the Royal 

 Institution*. 



IN a memoir by Professor Tyndall, read before the Royal 

 Society on the 17th of March 1864, it was shown that 

 when a carbonic oxide flame is used as a source of heat, the 

 absorption by carbonic acid is extremely large, even exceeding 

 that by olefiant gas, which with other sources is by far the most 

 powerful absorbent. Thus, of the radiation from heated lamp- 

 black, olefiant gas absorbs six times as much as carbonic acid; 

 whilst of the heat emitted by a carbonic oxide flame, the absorp- 

 tion by carbonic acid at small tensions is more than twice that 

 effected by olefiant gas at the same pressure. 



This very large absorption of heat by carbonic acid, suggested 

 to me the possibility of this method of experiment being applied 

 to the determination of that gas in certain cases where it existed 

 in small quantities. By the desire and under the direction of 

 Professor Tyndall I have made, with this view, several experi- 

 ments upon air and upon the human breath. As Professor 

 Tyndall is now in Switzerland, I publish the results at his 

 request, but without his supervision, and upon my own respon- 

 sibility. 



The apparatus used in this investigation consisted of the same 

 instruments (with the exception of the source of heat and " front 



* Communicated by the Author. 



